I keep hearing these terms, and it seems like both refer to the same thing: a greater probability of an event occurring at the extreme values of a distribution, far away from the mean (more than 3 standard deviations away)

**Answer**

The “heaviness” of the tail refers to how quickly the probability decays as you move away from the center of the distribution, while skewness deals with symmetry or lack thereof. For instance, the exponential distribution is skewed but considered to have a fairly light tail, while the Cauchy distribution is perfectly symmetric but heavy-tailed.

**Attribution***Source : Link , Question Author : Victor , Answer Author : dsaxton*